Unexpected furanose-pyranose isomerization of 4-C-alkylribofuranose

Abstract In this work, the attempt to synthesize 4-C-alkyl-S-ribosylhomocysteine (4-C-alkyl-SRH) analogues led to an unexpected and interesting intramolecular side reaction that occurred during the synthesis process. The detection of the compound 4-C-hexylribopyranose was confirmed by the use of 1H NMR and COSY spectra. The same reaction conditions were conducted for 4-C-octylribofuranose and led to the respective and 4-C-octylribopyranose. The 4-C-hexylribofuranose and 4-C-octylribofuranose were shown to exist in equilibrium with a ratio of 1:1 with their respective analogues 4-C-hexylribopyranose and 4-C-octylribopyranose.